Finding self worth and purpose

Your purpose is, at heart, a simple one – to be who God knows you to be. To be the active expression of love, kindness, wisdom, intelligence, goodness, and let's remember joy! Be who the infinite Mind of the universe has conceived in the amazing idea package called you.

“I am the place where God shines through
For He and I are one, not two.
He wants me where and as I am –
I need not fret, or fear, or plan.
And if I’ll be relaxed and free
He will express Himself through me.”
author unknown

Here's another view of why you are essential to God and His universe, "I am able to impart truth, health, and happiness, and this is my rock of salvation and my reason for existing."
Mary Baker Eddy, Miscellaneous Writings